ABS Injection Molding

September 26th, 2022

Injection molding, the most widely used process for mass manufacturing of plastic parts, works by injecting liquified molten thermoplastic under high pressure into a pre-shaped mold. Many kinds of materials can be used in injection molding to give the finished part the properties necessary for its intended end use. One such material, ABS, is a good example of a commonly used plastic injection molding material with benefits and limitations that should be taken into consideration when deciding if it’s appropriate for your part.

What Is ABS?

ABS is acrylonitrile butadiene styrene, a thermoplastic polymer. Each of the primary monomers that make up ABS give specific properties to ABS molded parts: acrylonitrile imparts hardness, as well as resistance to chemicals and heat; butadiene adds impact resistance and toughness; and styrene gives surface gloss, strength, and workability. As a thermoplastic, ABS can be heated to its melting point, cooled, and re-heated again without degradation, unlike a thermoset, which forms irreversible chemical bonds on its first heating. ABS is also amorphous, meaning that it does not exhibit the ordered characteristics of crystalline solids.

ABS is popular because it is relatively inexpensive and relatively easy to injection mold. Industries that use ABS injection molding include automotive, appliance, consumer goods, electronics, recreation, and sports. By changing the proportions of its components, different varieties of ABS can be made that exhibit different characteristics. The final properties of an ABS molded part can also be influenced by the conditions under which the material is processed. For instance, molding at high temperature improves gloss and heat resistance, while molding at low temperature provides the highest impact resistance and strength. These factors make it essential to work with an experienced injection molding manufacturer who can help specify the right grade and temperature for your project.

ABS Injection Molding Properties and Considerations

When preparing to use ABS for an injection molded part, it’s important to understand the properties of the material to avoid part defects in manufacturing. For example, ABS has a mold shrinkage of 0.004 to 0.007 inches and water absorption of 0.16% to 0.25%, which can affect curing and processing. Other considerations include:

Temperature control: When overheated, ABS can break down chemically. Operators must take care to keep temperature at the intended level.

Absorption value: ABS has a moisture absorption rate of 0.2 to 0.8%. Because dry ABS tends to absorb moisture, it should be dried prior to processing.

Injection pressure: While ABS requires higher injection pressures, too much pressure can cause excess friction. This will make it difficult to remove the part from the mold without damage to the part’s surface.

Injection speed: If ABS is injected too fast, the material can burn or decompose. If it’s injected too slowly, however, it may fail to fill the mold completely, leaving voids in the resulting part.

Viscosity: ABS’s viscosity, or its resistance to flow, is influenced by its melting temperature. Too little viscosity can make it difficult to mold, while too much viscosity can make results imprecise.

The Benefits of Injection Molding

Injection molding is a versatile process that has made it a favorite method for manufacturing production plastic components. It’s efficient, enabling the rapid production of many parts from a single mold once the mold is designed to the correct specifications. Plastic injection is also an automated process, requiring only the use of a single operator. Automation not only reduces the chance for human error, keeping the production of parts precise and accurate, but it also reduces the labor costs for a production run. Injection molding can also be used with a variety of different materials, including ABS, giving companies many options to meet the specific requirements of their application.

ABS Injection Molding Experts

At Southwest Plastics, we have over 55 years of experience in producing high-quality custom-made injection molded parts in our Southern California facility. Whether you’re looking to re-shore manufacturing from overseas or simply looking for a manufacturing partner that can consistently provide superior quality, competitive prices, and fast turnaround times, Southwest is the answer. Our engineering department has the experience and expertise to use any material, including ABS, to its best advantage in your injection-molded parts. To find out more about how Southwest Plastics can support your manufacturing needs with quality parts custom-made in America, contact us here.